Theory of Supramolecular Polymerization

Schoot, Ppam Paul van der; der, van

doi:10.1201/9781420027921.ch3

Cited by 40 publications

(82 citation statements)

References 67 publications

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“…Furthermore, when the heating and cooling curves were compared for these two solvents, almost overlapping data were obtained in MCH, but in decane a weak hysteresis was observed (Figure S2 in the Supporting Information), which is well known for cooperative supramolecular polymerization processes that occur by homogeneous nucleation. To gain more insight into this intriguing observation, the non‐sigmoidal cooling curve in decane was analyzed by using the variable size nucleation–elongation model where nucleation and elongation regimes are separated by the elongation temperature ( T e ). This model assumes the onset of supramolecular polymerization (at T > T e ) by a thermally activated unfavorable nucleation step (expressed with the dimensionless equilibrium constant K a , Equation ) followed by highly favorable elongation of the activated oligomers (at T < T e ; expressed with dimensionless equilibrium constant K a , Equation ).

true α_{agg} = α_{const} ([] 1 - \exp (\frac{- h_{e}}{R {T_{e}}^{2}} (() T - T_{normale})))

true α_{agg} = α_{const} ([], \sqrt[3]{K_{a}}, \exp, [(() \frac{2}{3 \sqrt[3]{K_{a}}} - 1) \frac{- h_{e}}{R T_{normale}^{2}} (() T - T_{normale})])

true ⟨ N_{normaln} ⟩ = \frac{1}{\sqrt{K_{a}}} ((), \frac{1 - \exp [\frac{- h_{e}}{R T_{normale}^{2}} (() T - T_{normale})]}{\exp [\frac{- h}{R T_{normale}^{2}} (() T - T_{normale})]})

…”

Section: Resultsmentioning

confidence: 99%

Solvent Geometry Regulated Cooperative Supramolecular Polymerization

Kar

Ghosh

2017

Chemistry A European J

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This article discloses hydrogen-bonding driven supramolecular polymerization of a core-substituted naphthalene-diimide derivative NDI-1, which exhibits J-aggregation in all tested hydrocarbon solvents; however, spontaneous gelation was noticed only in linear alkanes in contrast to free flowing solution in their cyclic analogs. Mechanistic investigation by variable-temperature UV/Vis studies and analyzing the data by using an appropriate model(s) elucidates a highly cooperative self-assembly pathway in linear hydrocarbons (heptane, octane, nonane, or decane) in sharp contrast to cyclohexane or methylcyclohexane in which an ill-defined polymerization was noticed. This is attributed to the direct participation of linear alkanes in the nucleation process by favorable mixing with the peripheral alkyl chains of the NDI monomer, which appears not to be the case for cyclic alkanes owing to geometry mismatch. Although all tested linear hydrocarbons induced nucleation-elongation growth, the thermodynamic parameters were found to depend on the chain length of the alkane. The morphology of the self-assembled polymer was strongly dependent on the growth mechanism as we noticed fibrillar networks and short-length rods, respectively, in decane and methylcyclohexane (MCH). However, in the presence of a small amount of additive (preformed fiber in decane; added in situ or post self-assembly) a fibrillar structure was noticed also in MCH, corroborating the self-assembly in solution, which adopted a cooperative mechanism similar to linear alkanes.

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true α_{agg} = α_{const} ([] 1 - \exp (\frac{- h_{e}}{R {T_{e}}^{2}} (() T - T_{normale})))

true α_{agg} = α_{const} ([], \sqrt[3]{K_{a}}, \exp, [(() \frac{2}{3 \sqrt[3]{K_{a}}} - 1) \frac{- h_{e}}{R T_{normale}^{2}} (() T - T_{normale})])

true ⟨ N_{normaln} ⟩ = \frac{1}{\sqrt{K_{a}}} ((), \frac{1 - \exp [\frac{- h_{e}}{R T_{normale}^{2}} (() T - T_{normale})]}{\exp [\frac{- h}{R T_{normale}^{2}} (() T - T_{normale})]})

…”

Section: Resultsmentioning

confidence: 99%

Solvent Geometry Regulated Cooperative Supramolecular Polymerization

Kar

Ghosh

2017

Chemistry A European J

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“…Assuming an isodesmic mechanism (37,54) in the self-assembly of compound 3a, the apparent association constant at 298 K is on the order of 5 · 10 5 M −1 in a concentration regime of 8 μM to 20 μM. Only a slight decrease to 3 · 10 5 M −1 is observed when switching to a 10-mM PBS buffer at pH 7.4 or a 50-mM succinate buffer at pH 6 (SI Appendix).…”

Section: Resultsmentioning

confidence: 99%

“…Various research groups, including ours, have reviewed models that allow the distinction between fundamentally different selfassembly mechanisms (36,52,(54)(55)(56). Based on the van der Schoot model (54), reliable fitting procedures (37) can provide us with the thermodynamic parameters describing the processes involved.…”

Section: Resultsmentioning

confidence: 99%

“…Temperature-dependent CD spectra in a 100-mM citrate buffer at pH 6: (A) discotic 1a (5 · 10 −6 M), (B) discotic 2a (2.5 · 10 −6 M) and discotic 3a (20·10 −6 M) and the resulting normalized and fitted CD cooling curves monitored at D λ ¼ 282 nm for discotic 1a, (E) λ ¼ 283 nm for discotic 2a, (F) λ ¼ 269 nm for discotic 3a. The lower three graphs show the normalized data as degree of aggregation Φ n vs. temperature: 0 refers to the molecular dissolved state and 1 to a fully polymerized system; red lines represent the best fits (37,54). Fig.…”

Section: Methodsmentioning

confidence: 99%

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Controlling the growth and shape of chiral supramolecular polymers in water

Besenius

Portale²,

Bomans

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

205

187

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A challenging target in the noncovalent synthesis of nanostructured functional materials is the formation of uniform features that exhibit well-defined properties, e.g., precise control over the aggregate shape, size, and stability. In particular, for aqueousbased one-dimensional supramolecular polymers, this is a daunting task. Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing out attractive noncovalent forces within the hydrophobic core of the polymerizing building blocks with electrostatic repulsive interactions on the hydrophilic rim we managed to switch from elongated, rod-like assemblies to small and discrete objects. Intriguingly this rod-tosphere transition is expressed in a loss of cooperativity in the temperature-dependent self-assembly mechanism. The aggregates were characterized using circular dichroism, UV and 1H-NMR spectroscopy, small angle X-ray scattering, and cryotransmission electron microscopy. In analogy to many systems found in biology, mechanistic details of the self-assembly pathways emphasize the importance of cooperativity as a key feature that dictates the physical properties of the produced supramolecular polymers.aqueous self-assembly | controlled architecture | supramolecular polymerization | dynamic materials M olecular self-assembly has emerged as a fascinating area in its own right (1, 2). A toolbox initially developed by supramolecular chemists quickly expanded into an interdisciplinary field aiming at the manipulation of matter at the molecular scale (3, 4). Up until recently self-assembly in dilute aqueous environments has predominantly dealt with linear amphiphiles that form closed structures (5-9), such as spherical micelles, cylindrical or rod-like micelles, and vesicles using, for example, phospholipids (10, 11), synthetic block copolymers (12, 13), or dendrimers (14). Morphological control in objects of defined size or shape, and transitions between different morphologies are increasingly well understood (15)(16)(17)(18). Surprisingly, however, the generality of these concepts has not been translocated into another area of increasing interest, namely, the self-assembly of one-dimensional arrays. In that context the development of discotic monomers has proven to be a valuable route to allow for the synthesis of rod-like supramolecular polymers (19), whose potential applications in functional soft matter include electronics, biomedical engineering, and sensors (20)(21)(22)(23)(24)(25)(26). Considering the enormous interest in such systems, it is surprising that efforts to control the size and shape of nano-and micrometer size one-dimensional objects are rare (27-29); successful strategies rely on the use of templates (30, 31), end cappers (32), or selective solvent techniques (33).In order to control the growth of aqueous one-dimensional supramolecular polymers, we propose to utilize electrostatic repulsive contributions in analogy to surfactant...

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“…The temperature dependence of χ pol is markedly different from the sigmoidal shape characteristic of isodesmic equilibria of classical equilibrium polymers. Instead, χ pol asymmetrically drops upon increasing the temperature and suddenly vanishes for values above a characteristic temperature (the polymerisation temperature T pol ), as expected in the case of nucleation–elongation polymerisation (sometimes called thermally activated equilibrium polymerisation), in which the polymer building blocks are mainly inactive, but subject to a thermal equilibrium with a highly active form that triggers polymerisation into (active) polymers …”

Section: Resultsmentioning

confidence: 66%

A Stereochemically Driven Supramolecular Polymerisation

Tasca

D’Abramo

Galantini

et al. 2018

Chemistry A European J

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Anthracyclines self-assemble in water into dimers. In the presence of sufficiently high salt (NaCl) concentrations, solutions of the antibiotic doxorubicin, but not those of the closely related molecules daunomycin and epirubicin, turn into gels barely compatible with the presence of small oligomers. The use of spectroscopic, scattering, imaging and computational techniques, allowed light to be shed on the self-assembly process that triggered doxorubicin gelification. A complex picture emerged, with doxorubicin molecules assembled into long, highly chiral, supramolecular aggregates made of hundreds of units, showing redshifted fluorescence spectra, very short fluorescence lifetimes and small-angle X-ray scattering profiles compatible with long cylinders. The involvement of specific chemical groups and the need for a specific stereochemistry of the monomers in the formation of a hydrogen-bond network to stabilise the supramolecular aggregates was supported by molecular dynamics calculations. A salt-induced, temperature-dependent, cooperative nucleation-elongation supramolecular polymerisation of the doxorubicin molecules is deduced.

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Theory of Supramolecular Polymerization

Cited by 40 publications

References 67 publications

Solvent Geometry Regulated Cooperative Supramolecular Polymerization

Solvent Geometry Regulated Cooperative Supramolecular Polymerization

Controlling the growth and shape of chiral supramolecular polymers in water

A Stereochemically Driven Supramolecular Polymerisation

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